I looked at the Novara bikes earlier this year when I was shopping and I searched for reviews on them here and on the web in general. My impression and that of most reviewers is that they are decent bicycles. I'd say their reputation is good and I considered them the equal of all the other similarly priced and equipped brands/models I was interested in. The model you are talking about looks similar in many ways to the Fuji I ended up getting from the LBS so you won't hear me dissing it. I'd say it is certainly worth considering and the REI website says the price is currently $599.93, not $670. As for the Trek, I am not familiar with them although on this forum I would expect that you will shortly get 10,000 people posting to tell you to consider nothing else....
Ken